Need engine help from the Guru's.....

[TonyDiaz_fls]

I just had to pick my 1991 GS up from the shop in pieces after waiting three months they showed me what my issue is.

Now I need help.

The head has fours caps that hold the cams. They are labeled A,B,C,D.  The one labeled "A" is broken in half.

The shop told me that the caps where installed in the wrong order and this could be the cause of the damage.

Questions:

Does anyone have this cap for sale?
What in addition to this cap would I need if I decide to attempt to assemble the motor myself (never worked on motorcycles) - Rebuild gasket kit? Do I need to hone the cylinders? Should I replace the piston rings?  

In addition, the shop said I had a 1mm piston - not sure if this meant 1mm over bore or dome.  
I'm sure someone here should know - Are the stock pistons flat tops? Mine have a dome.
Sorry if I input to many questions but I would really like to get my bike on the track next month.

Thanks for the help.  Tony.

[werase643]

the work is not difficult
the time line....
depending on how long it takes to get parts

call 305 687 moto
i think that is #
see if they can get you an engine quickly

[Freddy]

Hi Tony,

I will try and help you as much as I can from here ok, I have just rebuilt a GS500E 1995 engine, I also have some spares which may suit you.

The sequence for fitting the camshaft top half bearings is as follows, front camshaft (the one neares the front wheel) L/H side is "A" the R/H side is "B".

Rear camshaft L/H side is "C" R/H side is "D" the torque for the bearing bolts is 8-12 Nm.

Valve cover bolts torque = 13-15 Nm

The torque for the cylinder head nuts is 35-40 Nm.
You will need a Head gasket, 4 X "O" rings to go over the outer bolts these are part number Suzuki 11143 - 06B00

The part number for the head gasket is Suzuki 11141-01D10
The cylinder head bolts will have to be tightened in sequence and the sequence is in a X rotation from the centre outwards.
So, front centre left =1
Rear centre right = 2
front centre right = 3
rear centre left = 4
front extreme left = 5
rear extreme left = 6
front extrem right = 7
rear extreme right = 8

The bolts should be tightened in this sequence with a socket untill hand tight, then use a torque wrench to complete.

When the garage says you have 1mm pistons, then it's my guess you have oversise rings fitted already, and they may be trying it on.

If you need any further help, just call, hope this helps.

[dgyver]

The caps for the cams are line bored with the head. Mixing caps can be a bad thing, hence the reason that one broke.

The head has the tightening order stamped next to each bolt.

75mm pistons have a "1" stamped on top of them. Stock pistons are 74mm. I don't have a pic of the 74mm pistons handy.

[TonyDiaz_fls]

Thanks all.

I think I may have found a head from one of the guys in this forum.  The head has no valves but all the caps.

Dgvyer, Thanks for the pick of the piston.  I'll check tonight and see which I have.  Do you know - if I find a cap can the head and caps be line honed again?  

Another q:  Do you remommend honing the cylinders?

Freddy, thanks for the info.  Looks like I need a head.  I'll keep you posted.

[dgyver]

Your best bet is to get another head. I looked up about buying just the cap and they are not listed as available separate from the head. You may be lucky enough to get another "A" cap from another head and have it fit properly. I can see that a "C" cap in an "A" location would be a problem but maybe an "A" cap from a donor head would line up correctly with your head. Not something that I have looked into but I can check later tonight since I have several heads off of the motors.

If you do get another head and need to swap valves, look in the FAQ forum and there is my write-up of a valve spring compressor that you will need.

As for honing the cylinders, look at the cylinder walls for any scoring. This can be done without removing the cylinder. If you do hone the cylinders, I would recommend replacing the rings.

This reminds me to put together a pic of different pistons and their profiles.

[Bob Broussard]

I would go with another head, instead of trying to fit another cap.
If you look where the valve buckets go, you'll see the letters for each cap molded into the head.
I've never heard of a cap breaking. If they are in the wrong spot, it causes the cams to barely turn which could damage the bearing surface.
I've broken camshafts and beat the crap out a head and the cap never broke. No telling what was done to break this one.

Normally I would definately hone the cylinders and put new rings.
The problem is, if the pistons are 1mm overbore (factory pistons) then you can't get just rings alone. You have to buy new piston kits with the rings. :x

If you have to switch the valves to another head. Take the time to clean up the valves (remove carbon buildup) and use lapping paste to grind them into the seats. This takes a suction cup tool on the valve face spun back and forth by hand. Then be sure to put new valve guide seals on.

[dgyver]

Normally I would definately hone the cylinders and put new rings.
The problem is, if the pistons are 1mm overbore (factory pistons) then you can't get just rings alone. You have to buy new piston kits with the rings. :x

Are rings available from other sources, such as Wiseco?

[TonyDiaz_fls]

I'm trying to buy another head as we speak.  But when it comes to rebuilding the head I'm not sure if I could tackle that job.  I've never rebuilt a bike motor so I may need to find someone to rebuild the head or a least assist me with the rebuild.  I'll look at the FAQ forum.  If anyone has a head for sale please let me know.  Thanks.

[Bob Broussard]

I've compared the rings from my JE pistons to the factory ones and they don't match. The bore diameter is not the problem, it's the ring thickness.
If you measured the stock rings, maybe you could find a match.

TonyDiaz_fls

I have a pile of heads laying around. The problem is, I've scavenged the valves out of them to replace the ones I've damaged. So If you sent your head and cams to me, I'll build a good head for you. I'll use your valves and lap them in and install new valve guide seals. Then I'll set the valve clearences, so it will be a straight forward bolt in.
Lets say $50 plus shipping and parts (seals)?

[dgyver]

I measured the Suzuki rings and they are .047" (1.2mm). Wiseco makes rings in that thickness but not in 74 & 75mm diameters. Not familiar with other manufactures of rings. I remember someone mentioning that they used rings from a specific car.

Tony...better jump on that offer from Bob.

[TonyDiaz_fls]

Bob, sounds like a deal to me!  I sent you an email.  Thanks.